Transition of accretionary wedge structures around the up-dip limit of the seismogenic subduction zone
Transition of accretionary wedge structures around the up-dip limit of the seismogenic subduction zone
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DOI：
10.1016/j.epsl.2007.01.005
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发表时间：
2007-03
影响因子：
5.3
通讯作者：
G. Kimura;Y. Kitamura;Y. Hashimoto;A. Yamaguchi;T. Shibata;K. Ujiie;S. Okamoto
中科院分区：
文献类型：
--
作者：
G. Kimura;Y. Kitamura;Y. Hashimoto;A. Yamaguchi;T. Shibata;K. Ujiie;S. Okamoto
将南开三棱镜划分为外楔和内楔及其过渡带三段。这些楔形反映了楔形锥度、内部变形和底板边界断裂的不同方面。外楔以窄临界锥度为特征，内楔以序贯褶皱和逆冲变形为特征，并伴有地震变形。内楔为稳定的窄锥度，内部构造弱变形，基底有发震板块边界断裂。两个楔体之间的过渡带表现为大的临界锥度，表面坡度陡，内部构造为逆序逆冲，并向沉积-海基界面递进。海沟坡折和前弧盆地向海边缘位于该过渡带的陆缘附近。这些共同的方面可能与增生沉积和逆冲下沉积的岩化作用以及由此产生的板块边界断裂的开关有关。陆上增生杂岩的变形和岩化过程表明，板块边界的降压发生在发震俯冲带的上倾边界附近。
The Nankai accretionary prism is divided into three segments: outer and inner wedges and their transition zone. These wedges reflect different aspects of wedge taper, internal deformation, and basal plate boundary fault. The outer wedge is characterized by narrow critical taper, internal deformation by in-sequence-fold-and-thrust and aseismic décollement. The inner wedge represents a stable narrow taper, weakly deformed internal structure and seismogenic plate boundary fault along its base. The transition zone between the two wedges shows large critical taper with steep surface slope, internal structure of out-of-sequence thrust, and step-down of décollement onto the sediment–oceanic basement interface. The trench slope break and oceanward margin of forearc basin is located around the landward edge of this transition zone. These common aspects might be related to the lithification of both accreted and underthrust sediments and the resultant switch of the plate boundary fault. Deformation and lithification process recorded in exhumed on-land mélange of accretionary complexes suggest that the step-down of the plate boundary décollement occurs around the up-dip limit of seismogenic subduction zone.